Cookware coated with fluoropolymers, especially polytetrafluoroethylene (PTFE), has come into widespread use in recent years. Many cooks prefer to use such cookware because of its non-stick properties and because it is so easy to clean.
It is well known that the adhesion of fluoropolymers to metal is of a rather low order, so in the fabrication of such cookware it is customary to improve adhesion by applying a primer composition to the metal before applying the fluoropolymer topcoat. Such a primer composition is described in U.S. application Ser. No. 597,493, filed July 21, 1975now U.S. Pat. No. 4,016,125. The composition described there comprises
A. a fluoropolymer, PA1 B. a binder comprising an alkali metal silicate and the amine salt of a polyamide acid, PA1 C. a coalescing agent, and PA1 D. a liquid carrier.
While cookware primed with such a composition is quite durable, its entire fluoropolymer coating tends to become scratched after extended use.